1. Technical Field
The present invention relates in general to the field of computers and computer systems. More particularly, the present invention relates to a computer system adapted to deploy an application program. Also, the present invention relates to a method of deploying an application program in a computer system.
2. Description of the Related Art
In general, an application program is developed on a development computer system, and is then deployed on a host computer system where it will be run (executed). The deployment process turns the application into its final executable form, such as the creation of links between the application and any libraries upon which it relies. However, applications have become increasingly complex and are increasingly difficult to deploy. This leads to a very lengthy deployment process and/or to errors (e.g. crashes) in the execution of the host system. It is therefore desired to improve the stability and reliability of the system. Also, it is desired to reduce the significant workload which is involved in correctly deploying new applications onto the host system.
FIG. 1 is a schematic overview of an example computer network of the related art. Here, an application 1 is developed on a development system 4 and is then deployed on one or more host computer systems 2, using a deployment mechanism 3. The application 1 then runs on the host computer system 2 and, in this example, serves one or more individual end-user clients 5, either over a local network or via intermediaries such as a web server 6. The application 1 often will also communicate with various other back-end computers such as a set of database servers 7. FIG. 1 is only an illustrative example and many other specific network configurations will be apparent to those skilled in the art.
Application programs are often developed using object-oriented programming languages, such as the popular Java language developed by SUN MICROSYSTEMS. More recently, Java 2 Standard Edition (J2SE) and Java 2 Enterprise Edition (JEE or J2EE) have been developed to support a very broad range of applications from the smallest portable applets through to large-scale multilayer server applications such as complex controls for processes, manufacturing, production, logistics, and other commercial applications. Java relies upon a virtual machine which converts universal Java bytecode into binary instructions in the instruction set of the host computer system. Increasingly, applications are developed with the assistance of middleware such as the Spring framework (see www.sprinqframework.org) and are released as a collection of OSGi bundles (see www.osgi.org). Applications are configured using a variety of different techniques, in order to link to the other components of the increasingly complex and interconnected computer systems of the current art. For instance, an OSGi application configures imported packages using a JAR manifest, but the application may also be a web application which uses the Spring framework. Further, the Spring configuration may be provided in an XML file defining Spring beans. Thus, there is a real difficulty in deploying the application efficiently and correctly on the host computer system, such that the host system will execute the application safely and reliably, whilst taking account of these different various configuration mechanisms.